Fermentation profile and chemical composition of Mombasa grass silage treated with chitosan and microbial inoculant

Context. The ensiling process presents losses that are associated with the fermentative profile, resulting in lower nutritional value, and lower aerobic stability of silages. Aims. This study aimed to evaluate the effects of chitosan and microbial inoculants addition in Mombasa grass (Megathyrsus maximus) silage (MGS) fermentation profile and losses, chemical composition, in situ degradation, and aerobic stability. Methods. Forty experimental silos (PVC tubing with 28-cm inner diameter and 25-cm height) were used in a randomised block (n = 5) design to evaluate the following treatments: (1) MGS without additives (control, CON); (2) MGS treated with 5.0 x 104 colony-forming units (CFU) of Lactobacillus buchneri (NCIM 40788) per gram of fresh matter (LBB); (3) MGS treated with 1.6 x 105 CFU of L. plantarum and 1.6 x 105 CFU of Pediococcus acidilactici per gram of fresh matter (LPP); and (4) MGS treated with 6 g/kg DM of chitosan (CHI). Key results. The treatments did not alter the pH, ammonia-N, butyric, and lactic acid concentrations in the silage. The use of LPP reduced the ethanol content, while CHI increased propionic and branched-chain fatty acids compared with other treatments. Fermentation losses and dry-matter recovery were not affected by treatments. Chitosan reduced the organic matter of the MGS in relation to the other treatments, without having an impact on the other variables of chemical composition. The treatments did not influence the in vitro degradation, nor the pH and temperature after aerobic exposure of the silage. Conclusions. Chitosan increases ethanol compared with homofermentative lactic acid bacteria inoculation and does not affect ammonia-N of Mombasa grass silage. In addition, chitosan and microbial inoculants have limited effects on Mombasa grass silage fermentation losses, nutritional value, and aerobic stability. Implications. Chitosan does not reduce fermentation losses or improve the nutritional value of grass silage.